Introduction to the CohortFrom 1990 to 1993, investigators for the Rotterdam Study recruited residents in a suburb of Rotterdam, The Netherlands to participate in their longitudinal study of chronic disease in aging. They enrolled 7,983 adults, aged 55 years and older, of whom 7,046 were deemed to be free of dementia. Since enrollment, participants have undergone evaluations every 2-3 years. Additional follow-up information is available from medical record data. At enrollment, members of the dementia-free cohort were aged, on average, 69.5 years old (SD 9.1); 60% were female (Reitz 2007).

In 1971, investigators for the Gothenburg H-70 study recruited 70-year-old residents of Gothenburg, Sweden, in order to study normal aging and social and medical needs of elderly Swedish residents. Initially, investigators followed 937 participants (age 70, born in 1901-1902) for 30 years. Since this time, 4 additional birth cohorts of 70-year-old participants have been recruited. Many of these nwere participants have also been followed longitudinally. In 1986-1987, a representative sample of all 85-year-old residents of Gothenburg, including institutionalized residents, was recruited and followed. When cohort members were 88, they were invited to complete a follow-up interview. Follow-up of this sample is ongoing.

Data from these two studies were pooled in order to study the relationship between blood pressure and dementia (see Ruitenburg et al. 2001). Of the participants who were dementia-free at baseline, 60% were women, and on average, this sample was 69.3 years old.

Ethnicity BreakdownAll participants of the Rotterdam Study were residents of Rotterdam, The Netherlands. All participants of the Gothenburg H70 Study were residents of Gothenburg, Sweden. No other information on ethnicity or race has been reported.

Diagnosis & Evaluation MethodsFor a detailed description of diagnosis and evaluation methods in the Rotterdam Study, see Ott A et al 1998..

For a detailed description of diagnosis and evaluation methods in the H-70 Study, see Skoog et al (1993).